Messages in this thread | | | Date | Mon, 20 Dec 1999 01:24:46 +0100 | From | Ralf Baechle <> | Subject | Re: Thread-private mappings and graphics (was Re: Per-Processor Data Page) |
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On Thu, Dec 16, 1999 at 04:40:09PM -0800, Linus Torvalds wrote:
> Note that historically atomic locks have been EXPENSIVE. I think that was > true on MIPS too, even with the load-locked thing, just because with the > weak cache coherency the thing was initially done on the _bus_, not inside > the CPU. But happily that time is long gone, and it's not coming back.
ll/sc instructions on MIPS are as expensive as normal loads / stores.
(The pre-ll/sc thing SGI used in their R3000 based SMPs was horribly expensive, special purpose hardware that was of course different from other MIPS vendors' solutions and apparently at times needed *miliseconds* to do an atomic operation old SGIers told me ...)
Ralf
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